Variable resistance device



Feb. 7, 1939. u N. c. SCHELLENGER 2,145,953

VAR IAB -E HES ISTANCE DEVICE Filed Aprii 21, 1934 3 Sheets-Sheet l w H25 57 n 11153 95 M ZNVENTOR NEWTON U. 5 c1151: zzzvazfi.

A TT'Y.

Feb. 7, 1939. c. SCHELLENGER 2,145,953

" VARIABLE RESISTANCE DEVICE Filed April 21, 1934 37Sheets-Sheet s E 1NsUl-HT/ON 5235 34 EC; Jfl. E51].

INVENTOR.

NEW TON 6f SCHELLENGER. D1. 'MMZV- I ATT'Y.

Patented Feb. 7, 1939 UNITED STATES PATENT OFFICE Chicago TelephoneSupply 00.,

a corporation of Indiana Application April 21, 1934, Serial No. 721,1289 cm... (01. 201-55) This invention relates to a variable resistancedevice of the type-in which an actuating arm moves a contactorover, theredstance element andapplies more particularly to variable resistancedevices of thetype used in volume control or tone control circuits inradios or public address systems. v

It has often been found-desirable to actuate other control devices,positioned in near proxi imity to the variable resistance device, by thesame actuating meanswhich is used to operate the variable resistancedevice.

I am. aware of the fact that others have proposed various means for theactuation of coni trols arranged adjacent to a variable resistancedevice such as the transient operation of a switch or the actuation of aseries of similar controls arranged in tandem relationship by means asingle actuating member. But in all these prei viously proposed devicesthe single actuating means is positioned, relative to the variableresistance control and the additional control so that a completeactuation of one of thecontrols must of necessity also actuate the othercontrol as or controls. In other words, the various controls to beactuated by the single actuating means were arranged in such operativerelationship to the latter that when one of the controls is actuated inits entirety the other control or con- 30 trols must of necessity alsobe operated. In a plurality of adjacent controls, -all of which are tobe actuated by a single actuating means, it may often be desirable torefrain from actuating one or more ofthe controls even though theadjacent control or controls are actuated in their entirety. b It is anobject of the present invention to provide a variable resistance controldevice with an actuating means which at the option of the op- 40 eratormay be made to actuate an adjacent control device, but which need notactuate the adjacent control device even though the variable resistancedevice is actuated throughout its-full range.

45 It is another object of this invention to provide a single actuatingmeans for a plurality of control devices which actuating meansis'normally arranged for actuation of one or more control devices butwhich upon being actuated 50 in a particular manneris adapted to actuateone or more additional control devices. f

It is a further object of my invention to provide an enclosed resilientelement for maintaining the actuating means of a control device-in a 1normal operating relationship wit on or more control devices and uponapplication of force against said resilient element the actuating meansis adapted to be placed in operating relationship with one or moreadditional control devices.

, It is a further object of my invention to provide a substantiallyenclosed, electrically shielding coverfor a control device having arotatable and axially movable actuating means and means integral withsaid cover operable as a journal bearing and thrust bearing for anactuating shaft. 7

It is a further object of my invention to provide a control device witha metallic cover member having stop elements for limiting the move- 16'ment of the control mechanism struck therefrom at such portion of saidcover member which has the greatest supporting strength for said stopelements. A further object of my invention is to pro- 20 vide a controldevice having an actuating shaft and bearings for said shaft, positionedat extreme opposite portions of said device so as to afford the maximumsupport for said shaft and to prevent binding of said shaft upon slightdefeotivealignment of the bearings.

It is a further object of my invention to provide a variable resistancedevice having a rotatable and axially movable actuating means and aresilient contact arm adapted to expand in unison so with the axialmovement of said actuating means to maintain a driving engagement withsaid actuating means and maintain electrical contact between aresistance element and a plurality 01' current conducting members in allaxial positions of said actuating element. 7

It is a further object of my invention to provide a variable ce devicecomprising a rotatable and axially movable shaft and a substantiallyenclosed metallic housing for electri- 4o cally shielding said variableresistance device from associated control devices.

Another object of my invention is to provide a variable resistancedevice housing in which parts of the housing may be fastened to eachother without leaving any undesirable and unsightly parts projectingtherefrom.

Still further advantages of my invention will become evident byreference to the following description taken in connection with theaccompanying illustrations of one specific embodiment thereof, the.scope of the invention to be limited only as deflned'by the appendedclaims.

g In the drawings: I

Fig.1 is a planview of a variable resistance device constructed inaccordance with my inventicn, with the top of the housing and theresilient spring member removed to show the relationship of the variousparts.

Fig. 2 is a vertical sectional view, taken along line 2-2 of Fig. 1, andshowing the shaft in its normal position spaced from the thrust bearing.

Fig. 3 is a vertical sectional view similar. to Fig. 2 and showing theshaft forced into position against the thrust bearin'g.

Fig. 4 is a top plan view, on a slightly reduced scale, of the variableresistance device shown in Fig. 1 with the shaft shown in sectionadjacent the top of the housing.

Fig. 5 is abottom plan view of the device shown in Fig. 1 andillustrating the means of connecting the housing to the grounding plate.

Fig. 6 is a vertical elevational view of the device shown in Fig. 4.

Fig. '7 is an exploded isometric assembly view of a variable resistancedevice constructed in accordance with the invention and illustrating therelationship of the various parts to each other.

Fig. 8 is an enlarged fragmentary view of a section of the groundingplate at an intermediate stage of manufacture.

Fig. 9 is a sectional view taken along the line 99 of Fig. 8.

Fig. 10 is an enlarged fragmentaryview of a the cup-shaped controlhousing for the variable resistanc'e control. The control housing 20 isprovided with a circular, substantially flat .end wall 2! from whichextends a cylindrical side wall 21 (see Fig. 7). The free edge of theside wall is provided with a plurality of extensions 2| spaced from eachother and hereinafter referred to as ears. A section 22 of the free edgeof the cylindrical side wall (see Figs; 3 and 7) is cut away to preventcontact with the current carrying terminals of the variable resistancedevice. Stop members 23 are struck from the side wall of thehousing.These stop members for limiting the angle of rotation of the controlmechanism must be of substantial height and .are therefore struck from asection of the side wall which is spaced a substantial distance from thecut away section 22, in order to provide the necessary strength andrigidity to these stop members.

The central portion of the housing is provided with an annular depressedportion 25, substantially U-shaped in cross-section, the innermostportion of which consists of a cylindrical section I 25 which isconcentric with the cylindrical side wall 21 of the housing. The innersurface of section' 26 is constructed to fit snugly about the reducedportion 81 of a shaft 36 and is adapted to function as a journal bearingfor said shaft. The flatinner surface 25a of the annular depressedportion 25 is adapted .to function as a stop member and thrust bearingfor shoulder 38 of the shaft 36.-

An insulation strip 28 having narrow slots 29 of strip28 will abutagainst the end wall 24 of the housing whereas the opposite edge of thestrip will abut against an insulating base plate 96.

The base plate 96 is provided with an integral arcuate, extended shelfsection 98 and supported on the base plate is a resistance element 91.In the particular embodiment disclosed herein, the resistance element isof the planar carbonaceous type although other known types of resistanceelement may be used equally well to fulfill the requirements of thisinvention. The planar, car"- bonaceous type, resistance element 91 maycomprise a coating of carbon or graphite composition 11 on a sheet of,tough, yieldable, insulating material such as parchment paper as isclearly illustrated in Figs. 1 and 2. The resistance element is providedwith a break 89 between the ends thereof, or may comprise a coating ofsuitable carbonaceous resistance material applied directly onto the baseplate. 7

A substantially circular metallic grounding plate 98 is positioneddirectly on the rear surface of the base plate. The grounding plate 98is provided with a plurality of tongue sections 93 spaced from eachother on the outer marginal periphery thereof. The tongue sections areflattened so as to produce depressed offset portions on the outersurface of the grounding plate.

These offset tongue portions 93 are produced by cutting sections fromthe outer periphery of the grounding plate thereby leaving a pluralityof pairs of parallel sided notches 83, 84 and a tongue 94 which isshorter than the circumference of the main portion of the groundingplate (see the dotted line in Fig. 8.) The tongue 94 is then flattenedby pressing the same to the desired thickness, forcing themetal of thetongue into a part of the space of matches, 84 and the tongue is alsothereby lengthened to extend substantially to the circumference of themain portion of the plate. A section 92 (see Figs. 5 and 7) of thegrounding plate is cut away to prevent contact with current carryingterminals 19, 85, 19 of the variable resistance device. A plurality oflocating projections 95 (see Fig. 6) are formed on the outer surface ofthe grounding plate. These projections 95 are adapted to fit intosuitable apertures lll8 of a panel ID! or other supporting surface,whereby the variable resistance device may be easily, quickly andaccurately positioned against a panel or surface to which it is to befastened. y

The grounding plate is adapted to reinforce the base plate as well as toconstitute a metallic cover for the housing to electrically shield thevariable resistance device from electrical dis"- turbances of adjacentdevices.

The base plate 96 and the grounding plate are constructed with openings88 and 9| respectively for cooperation with a circular bushing 19. Thebushing 10 is formed with an externally threaded portion 12 forconnection of the same to a panel or the like, and is provided with ananflange 19a and the shoulder 15 is fitted in the openings 88 and 9| ofthe base plate and ground-f ing plate respectively with the sharp ridgell of grounding plate and thereby securely fasten the base plate andgrounding plate together.

The housing is securely fastened to the grounding plate by bending. theears 2! thereof over onto the depressed tongues 93 of the groundingplate thereby forcing the base plate firmly against the insulation strip28. The ears 2| are adapted to be retained within the said depressedtongue. portions 93 of the grounding plate, thereby providing a smootheven outer surface on the 15 said plate 90. This even outer surface willpermit connection of the variable resistance device to a panel or otherplane surface without distortion of the grounding plate or base platewhen it is drawn up tightly against the panel I01 by screwing a nut I09onto the threaded portion 12 of the bushing projecting through anopening I Ill of the panel.

The bushing 19 has a longitudinal bore through the center thereof. Thegreater part of the length of said bore is preferably of a diameterconsiderably larger than the external diameter of the shaft 36 so as toprovide a very loose fit with the shaft 36. The end of the bushingextending from the variable resistance device contains a comparativelyshort bored section 13 of a diameter \very, slightly larger than theexternal diameter of the shaft 38 so as to constitute a journal bearingfor the shaft. The shaft extends through andv has a portion thereofprojecting from the vbushing to constitute a handle for imparting axialor rotatable movement to said shaft.

When the two journal bearings 25, I3 for the shaft are positioned atextreme opposite sides of the varpble resistance device as disclosed inthe preferred embodiment of the invention, a much greater rigidity andstability is imparted to the shaft than would be possible if thebearings were positioned closer together. Furthermore, the exactalignment of bearings is not as critical and the allowable tolerancesneed not be so close when the bearings are comparatively short and arespaced a substantial distance from each other as would be the case ifthe bearings were long or spaced close together.

The arcuate extended shelf section'98 of the base plate 96 contains aplurality of parallel sided notches I34, I05 and Ill (see Figs. 3 and 5tin which are positioned a plurality of current carry-.

ing terminals I9; I9, and 35. The grounding plate which overlies thebase plate has the section 92 thereof removed to prevent making contactwith these'terminals. The end terminals 19, I9 are positioned intonotches I94 and I08 and are .0 adapted to contact the ends-ofthe'resistance elefiled February 17,1934;

As pointed out above, the actuating shaft 39 is reduced in diameteradjacent the end wall. of the housing, the reducds'ection 31 of theshaft extending through and projecting from p the said end wall 24. -Adrive arm 39 is fixed to the main portion of shaft adjacent the reducedportion thereof.

The drive arm 39 comprises a fiat plate having an integral cylindricalcollar portion 40 formed' therein, the collar portion 40 being arrangedperpendicular to the flat surface of the plate and may be formed bydrawing the same from the One end of t e plate' metal of the flat plate.terminates in a downwardly directed nger 4| and the other end of theplate terminates in a blunt section having oppositely directed sides 44,45. A second downwardly directed finger 42 is formed on the armintermediate the collar 40 and the sides 44, 45. This finger 42 ispreferably spaced from the collar 40 a distance equal to that betweenfinger 4| and the collar 40. In order to construct the finger 42according to exact dimensional requirements by a punching operation, itis preferable that a section of the metal surrounding the finger befirst removed to leave a finger of the exact desired dimensions whichmay then be bent downwardly to the position shown in Fig. '7 of thedrawings. The inner surface, of the collar 49 is knurled or otherwiseprovided with axially extending teeth 46 (see Fig. 2) which are adaptedto be forced into the metal of the shaft 36 when the arm is forcedthereon, and thereby dispenses with the necessity of fastening elementssuch as set screws or key members between the shaft and arm. If desired,similar teeth 46a may be provided on the shaft for coengagement or tomesh with the teeth 46 of the drive arm.

The fingers 4| and 42 of the drive arm are 3 adapted to fit into notches49 and 43 respectively of a motion-transmitting plate. Thismotiontransmitting plate is made of insulating material and has anopening 52 into which the shaft 36 is positioned and thus permitting thefingers of the drive'arm to engagethe sides of the notches 49 and 48.The plate 41 is considerably wider than the drive arm 39 as is clearlyshown in Fig. 1, and at least one end of this plate is arranged tosubstantially overlie the converging ends of the resilient contact armmembers 53, 59 to prevent dislodg'ing of the contact shoe in case ofviolent vibration. For simplicity in assembly, both ends of the plateare constructed alike. The plate 41 is further provided, on oppositesides thereof, with notches and 5! for engagement with upstandingprojections 54, 54 of a contactor arm 53 and thereby transmit motionfrom the drive arm 39 to the contactor arm 53.

The contactor arm 53 is composed of resilient metallic material havinga'substantially circular slip ring portion with an opening 56 thereinwhich is sufiiciently large that the shaft 36 may extend therethroughwithout contacting the sides of the opening. A pair of comparativelylong converging arms 58, 58 extend from the slip ring portion and arejoined at their converging ends. Extending from the junction of theconverging ends is a downwardly directed toe 51 whichis adapted toproject into an opening 6| of the contact shoe 60. The contact shoe isconstantly maintained in contact with the resistance ele-. ment 11, andis pressed against the resistance element by the resilient contactor arm53. The upstanding projections 54, 54 are adapted to prevent contact ofthe contactor arm with the shaft by their engagement with the notches53, 5| of the motion-transmitting plate. The projections 54, 54 areprevented from making contact with the drive arm 39 due to the fact thatthe plate 4'I is-wider than arm 39. The contactor arm is bent, warped ordished so as to function as a the resistance element 'I'I as will bemore particularly described below.

A collector ring 62 is positioned directly below the body portion of thecontactor arm 53 and is constructed to substantially the same size asthe slip ring portion of the contactor arm so as to be constantlymaintained in contact therewith. An extending arm 65 is provided on thecollector ring (see Fig. 3) which terminates in a narrow finger portion66. This finger portion 66 is adapted to be projected through a smallopening 81 in the end 86 of the central terminal 85. The end 86 of theterminal is'then bent over onto the base plate thereby clinching the end86 and the finger 66 securely together. Care must be taken to preventcontact between the resistance element and the bent over end 86 of theterminalf. This may be done, as shown in Fig. 7, by cutting out asection I6 of the resistance element. The collector ring 62 is providedwith alarge opening 61 of substantially the same size as opening 56 ofthe contactor arm, and also with guide projections 63, 64 to preventcontact of the collector ring with the shaft 36. An insulating washer 68is positionedbetween the collector ring 62 and the circular bushing I0for the purpose of preventing contact between the collector ring andbushing. The washer 63 is slightly larger in diameter than the flange10a' of the bushing so that the: downwardly directed guide projections63 and 64 of the collector ring will be prevented from contacting theflange 10a. The guide projections 63, 64 engage diametrically oppositeportions of the insulating washer 68 to thereby prevent contact of anyportion of the collector ring with the shaft 36.

A dished spring member 3| having a plurality of outwardly directed arms32 and a centrally positioned opening 33 for the shaft 36 is positionedbetween the drive arm 39 and the end wall 24 of the housing to normallymaintain .the shaft in the position shown by Fig. 2, with the drive arm,motion-transmitting plate, contactor arm, collector ring and insulatingwasher all forced into close contact with each other and against theflange 10a of the circular bushing. A washer 34 preferablyformed ofinsulating material, may, if desired, be positioned between the spring3| and the drive arm 39. The washer 34 is provided with a centrallypositioned opening 35 sufliciently large to snugl fit about the collarof the drive arm.

An actuating arm I00 may be mounted on the reduced end 31 of the shaftwhich projects from the end wall of the housing. This arm I00 can befixed to the reduced end of the shaft in any in Fig. 2. In order toactuate the adjacent control device 'the shaft 36 must be moved axiallyagainst the action of spring 3|, that is, before the eccentricallymounted projection |0| can engage the element I03 of the adjacentcontrol, the shaft must be moved axially to the position shown in Fig.3.

It will beobvious that many other means of driving engagement of thereduced end of the shaft with an adjacent control device, for operationof the control device when the shaft is in its advanced axial position,may be devised by anyone skilled in the art and the specific embodimentherein disclosed is for illustrative purposes only and the invention isnot to be limited thereby.

When the shaft'is moved axially against the action of spring 3|, asshown in Fig. 3, the shoulder 38 of the shaft is adapted to contact thesurface 250. of the thrust bearing, the surface 25a functioning both asa means for limiting the axial movement of the shaft as well asproviding a surface against which the shoulder 38 may turn. It will befurthermore readily apparent that when the shaft is forced against thethrust bearing the resilient contactor arm will assume its natural bentor dished shape so as to maintain a contact with the collector ring aswell as maintaining a pressure on the contact shoe to preserve anelectrical contact between the latter and the resistance element.

' As has been pointed out above the stop members 23, 23 are struck fromthe sidewall of housing 20 at a substantial distance from the portion 22of the side wall which is removed to prevent contact with the terminals.The stop members 23, 23 are positioned to be engaged by cars 44, of'thedrive arm 33 when the contact shoe is adjacent an end of the resistanceelement. Inasmuch as the drive arm willbe moved axially with the shaft,the stop members 23 must be of considerable height to insure engagementat all times with the ears ll, 45 of the drive arm 33 and it isprimarily for this reason. that the members 23 are struck from thehousing'at a distance from the cut-out section 22.

In this connection it willbe noted that the-rotational movement of theshaft andassociated elements is limited by direct impact of the drivearm against the stop members. The drive arm is directly connected to theshaft in a very rigid manner, consequently there is much less danger ofdamaging the control device by the shock of the impact with the stopmembers than if some other element of the device were used as a meansfor limiting the rotational movement.

In the operation of the variable resistance device herein disclosed,when used as a simple rheostat, the current is adapted to pass from anend terminal to the resistance element, .then to the contact shoe, thento the contactor arm, from the contactor arm to the collector ring andfrom the collector ring to the central terminal. When the shaft is inits normal retracted position shown in Fig. 2, rotation of the shaftwill actuate only the variable resistance device.' If the, shaft isrotated in a clockwise direction, the side 45 of the drive arm willeventually abut against one of the stop members 23, 23 at which positionthe contact shoe will be adjacent one end of the re-- sistance element.Upon'rotation in the other direction the side 44 of the drive arm willabut against the other stop member and the contact shoe will bepositioned adjacent the other end of the resistance element. It ispreferable that the contact shoe can be moved on the'resistance elementadjacent portions 82, 82 of the terminals without making a contact withthe same, as any direct contact between the end terminals and the shoeis undesirable.

The contact shoe is moved over the resistance element by means of thecontactor arm 53. The

' rigidity to the entire device and to eliminate a binding of theaxially and rotatably movable shaft because of slight inaccuracies inthe manufacture of the various parts, the journal bearings for the shaftare spaced from-each other as far as possible in opposite extremepositions of the housing and bushing. Thrust bearing means are providedin the housing adjacent the journal bearing, to function as an impactabsorbing means, and to aid in withstanding the endwise rotationalthrust of the shaft.

In the modified form of variable resistance device shown in Fig. 12, theshaft 36' is mounted in the housing 20 and its associated bushing 10'for rotational movement only and illustrates the manner in which thecontrol device may be constructed in a narrow compact unit when theaxial movement of the shaft can be dispensed with. This modifiedconstruction retains the advantages of the other features of theinvention to provide an exceptionally rugged, uniformly and smoothlyoperating unit, which can be constructed very economically and withoutthe usual critical requirements of variable resistance devices knownheretofore that each individual element be maintained within severelyfine tolerances.

The shaft 36 is supported by the widely separated comparatively shortjournal bearings 26' of the housing 20' and 13' of the bushing 10'. Asin the case of the variable resistance device shown in Figs. 2 and 3,this feature will permit smooth, uniform rotation of the shaft eventhough there is a slight malalignment between the two bearings. Theshoulder 38 of the shaft will be continuously maintained in directcontact with the thrust bearing 25', thus permitting a considerablenarrowing of the side wall of the housing. If an exceptionally smoothoperation is desired, a small, smooth thrust washer I05 may bepositioned between the shoulder 38' and the thrust bearing 25'. When noadditional control is positioned adjacent the variable resistance devicefor actuation by the shaft 36' the'reduced end of the shaft 3'! may beout off evenly with the end wall 24 of the housing 20' as shown in Fig.12. Nevertheless, it will be obvious that the reduced end of the shaftmay be extended beyond the end wall 24' for thepositive actuation of anadjacent control in a known manner. It is not necessary that the stopmember 23' be made as longas stop member 23 by reason of the fact thatthe drive arm 39' is not moved axially as is drive arm 39 in themodification described above, nevertheless it is preferably struck froma portion of the housing spaced from the terminals to prevent cuttingthrough the free end of the side wall of the housing as would be thecase if it were struck from the section of the'housin adjacent theterminals.

The grounding plate 9.0 is provided with depressed tongues 93'.corresponding to the depressed tongues 93 as previously described, andthe ears 2| of the housing'are bent over onto the tongues 93 so as toprevent troublesome projections on the external free surface of thegrounding plate 90.

The various other parts of this modified construction of variableresistance device are constructed and assembled inthe same manner andrelationship as above described with references to Figs. 1-11.

It is to be understood that the specific embodiment of the inventionillustrated and described may be varied in many details of itsconstruction within wide limits without departing from the spirit of theinvention, and that the invention is to be limited only within the termsof the appended claims.

I claim:

1., A variable resistance control device havin in combination, ahousing, a shaft rotatably mounted in said housing, a journal bearing inone side of said housing, a bushing extending from the opposite end ofthe housing, a narrow journal bearing in the outer end of the bushing,said journal bearings being positioned at extreme opposite ends of saidhousing, whereby main'mum rigidity with minimum bearing surfaces may beobtained between said shaft and bearing in the bushing and the bearingin the housing.

2. A variable resistance device having in combination, a metallicopen-ended housing member, a metallic plate overlying the open end ofsaid housing member, said metallic plate being formed with a pluralityof peripherally arranged tongues depressed below the plane of theexterior face of said plate, a plurality of ears integral with saidhousing member, said housing and plate being secured to each other bybendingsaid ears over onto said depressed tongues, and an actuatingshaft extending through said plate and housing.

3. A variable resistance device having in combination, a metallicopen-ended housing, a plurality of ears extending from the open end ofsaid housing, a metallic plate adapted to close the open end of saidhousing, a plurality of tongues at the marginal periphery of said plate,said tongues being depressed below the plane of the exterior surface ofsaid plate, said housing and plate connected to each other by bending ofsaid ears over onto said depressed tongues whereby an even exteriorsurface is provided on said plate.

4. A variable resistance control device having in combination, a housinghaving a perforation therethrough and an annular depressed portionimmediately surrounding said perforation, a resistance element in saidhousing, contacting means cooperating with said resistance element,.

means for actuating said contacting means including a rotatable shaftextending into said housing, said annular depressed portion constitutinga combined journal and thrust bearing for said shaft.

5. A variableresistance device having in combination, a cup-shapedmetallic housing having a cylindrical wall, a variable resistance insaid housing, a rotatable contact driving member in said housing, lugsstruck' inwardly from the wall of said housing, a strip of insulatingmaterial against the inner surface of the cylindrical wall of thehousing, the lugs extending through the insulating material to positionthe same, the insulating material covering the openings in the housingwall from which the lugs are struck, and portions on the rotatablecontact driving member adapted to engage the lugs to limit rotation ofsaid member.

6. A variable resistance device having in combination, a housing, aresistance in said housing,

housing for an end surface of the shoulder on said shaft, stop meanslimiting movement of the shaft in the direction away from the secondbearing, the contactor being maintained in ena shaft extending throughat leastione wall of gagement with the resistance strip throughout saidhousing, a contactor engaging the resistance axial movement of theshaft, means for yieldingly and moved by rotation of the shaft, meanscarmaintaining the shoulder spaced from the second ried by the shaft androtatable therewith conbearing, actuating means on the end of the shaftnected to the contact, said means engaging a fixed beyond the secondbearing, and a second control connector carried against the inner faceof one device located to be actuated by said means when 10 Wall of thehousing, and resilient means engagthe shaft is in engagement with thesecond ing the opposite inner wall of the housing to urge bearing. saidfirst means against the fixed connector and 9. A multiple circuitcontrol device comprising toward the first wall. a variable resistancehaving in combination, a

7. A variable resistance device having in comhousing, a shaft rotatablymounted in and exbination, a housing, a resistance in said housing,tending through said housing, a resistance strip a shaft extendingthrough at least one wall of in the housing, a contactor engag the ssaid housing, a contactor engaging the resistance ance strip and rotatedby the shaft, a shoulder and moved by rotation of the shaft, conductingon said shaft, a journal bearing formed integrally means connected tothe contact and carried by with said housing at one end thereof, asecond and rotatable with the shaft, a second conducting journal bearingat the opposite end of said housmeans carried by an inner wall of thehousing, ing, a thrust bearing formed in the wall of said and resilientmeans engaging the opposite inner housing adjacent said first-namedjournal bearwall of the housing and urging the shaft toward ing withinthe housing, stop means limiting movethe first-named Wall to causecontact between the ment of the shaft in the direction away from thesaid conducting means. i thrust bearing, the contactor being maintainedin 8. A multiple circuit control device comprising ng em nt with the rsis an e strip throu h a variable resistance having in combination, aaxial movement of the shaft, means for yieldingly housing, a shaftrotatably mounted in and exmaintaining the shoulder spaced from thethrust tending through said housing, a resistance strip bearing andagainstsai p e a ati in the housing, a contactor engaging the resistancestrip and rotated by the shaft, a shoulder on said shaft, a bearingsurface integral with said housing for a circumferential surface of saidmeans on the end of the shaft beyond the second nearing, and a secondcontrol device located to be actuated by said means when the shaft is inengagement with the thrust bearing.

shaft, a second bearing surface integral with said NEWTON C. SCHEUENGER.

CERTIFICATE OF CORRECTION. Patent No. 2,1Lr5,955c February 7, 1959.

' NEWTON C. SCHELLENGE R.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correctionas follows: Page 5,second column, line 25, claim 1, for "bearings" read bearing; lines 27and 28,

strike out the words "in the bushing and the bearing in the housing" andinsert the same before "being" in line 25,same c1aiml; and that the saidLetters Patent should be read with this correction therein that the samemay conform to the record of the case in the -Patent Gffice. Signed andsealed this 11th day of April, A. D. 1959.

Henry Van Arsda'le (Seal v Acting Commissioner of Patents.

